Light emitting diodes (LEDs) and organic light emitting diodes (OLEDs) are rapidly emerging as a substitute for conventional light sources due to excellent energy efficiency and long lifespan thereof. Generally, a light emitting diode in combination with components such as a reflector, a reflector cup, a scrambler, and a housing forms a light emitting diode package to maximize light efficiency through high reflectance. Such components must be able to withstand high temperatures and to minimize degradation in reflectivity and degradation in whiteness due to yellowing.
As engineering plastics, polyester resins, copolymers thereof, and blends thereof exhibit useful properties and are thus applied to various fields including interior/exterior materials of products and are also used as a material for the aforementioned components. Particularly, highly heat-resistant polyester resins such as wholly aromatic polyester resins are generally used as a material for the above components. Such a highly heat-resistant polyester resin is not deformed at high temperature and has excellent discoloration resistance, but has a low crystallization rate, low mechanical strength, and low impact resistance.
In order to solve these problems, there has been proposed a method in which additives such as inorganic fillers are mixed with a polyester resin to improve impact resistance and stiffness. However, when additives such as inorganic fillers are used in excess, degradation in moldability, such as bleed-out, can occur.
In addition, in order to obtain a thermoplastic resin composition capable of realizing a high reflectance, the content of a white pigment should be increased. In this case, however, impact resistance of the thermoplastic resin composition can deteriorate due to excessive addition of the white pigment, inorganic fillers and the like.
Therefore, there is a need for a thermoplastic resin composition which does not cause the above problems so as to be used as a material of components for a light emitting diode while exhibiting excellent properties in terms of reflectance, impact resistance, stiffness, and balance therebetween.